#include <bits/stdc++.h>
using namespace std;
int a[100010];
int main() {
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }

  int d = a[2] - a[1];
  for (int i = 2; i <= n; i++) {
    if (a[i] - a[i - 1] != d) {
      cout << "No" << endl;
      return 0;
    }
  }
  cout << "Arithmetic Sequence" << endl;

  return 0;
}